Olympus Mons Fan Shaped Deposit Morphology: Evidence for Debris Glaciers
نویسنده
چکیده
Introduction: Olympus Mons is the largest volcano on Mars, rising over 25 km above the surrounding plains and with a basal diameter greater than 600 km. It is surrounded by a basal escarpment up to 6 km tall. Extending up to 1000 km beyond this scarp are lobes of ridged materials known as the aureole [1, 2]. Superimposed upon the west and northwest aureole deposits at the base of the escarpment are lobate features which are often interpreted to be landslide debris aprons [2, 3]. In 1981, Lucchitta [4] demonstrated that the morphology of these marginal fan shaped deposits as revealed in Viking imagery is very similar to terrestrial glaciers. The location of these deposits is shown in Figure 1. The fan shaped deposits found on the northwest flank of Olympus Mons show long, even, curvilinear ridges which are subparallel to the deposit margins. These ridges sharply contrast with those associated with landslide deposits, which are characterized by longitudinal groves or transverse ridges. The ridges on the northwest flank debris apron exhibit similar morphology to ridges of moraine material found near the margins of terrestrial glaciers (Figure 5b in [4]). An additional deposit found at the base of the west scarp displays a tongue-shaped center with subparallel lobate ridges towards the margins. These ridges are superposed on the surrounding aureole and are not deflected by the topography; thus Lucchitta interprets them to be draped over the surface as a debris-rich or rock glacier decayed [4]. In this study we expand upon Lucchitta’s hypothesis. A range of glacial emplacement mechanisms are considered.
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We use Viking and new MGS and Odyssey data to characterize the lobate deposits superimposed on aureole deposits along the west and northwest flanks of Olympus Mons, Mars. These features have previously been interpreted variously as landslide, pyroclastic, lava flow or glacial features on the basis of Viking images. The advent of multiple high-resolution image and topography data sets from recen...
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تاریخ انتشار 2003